Removal of excess liquid from wet film



June 7, 1949. c. J. KUNZ REMOVAL OF Patented June 7, 1949 REMOVAL OF EXCESS LIQUID FROM WET FILM Charles J. Kunz, Rochester, N. Y., asslgnor to Eastman Kodak Company, Rochester, N. Y., a

corporation of New Jersey 7 Application May 17, 1946, Serial No. 870,836

The present invention relates to the art of drying continuously-moving webs, and particularly to a method and apparatus for removing excess liquid from the surface of a processed photographic film.

wringer rollers and air squeegees have been extensively used in film-processing machines to remove the excess processing fluid, and particularly the wash water from the surfaces of the film to expedite a rapid drying of the film. Although wringer rollers are effective in removing the greater part of the loose water adhering to the surface of a photographic film, ordinarily they are not as effective in removing the last trace of surface liquid as a correctly-adjusted air squeegee.

It is well known that when wringer rollers are used, a quantity of liquid collects along the line where the film enters the nip between the rollers, that is, on the upstream or wet side; I have found that on the downstream or "dry side of the rollers, another smaller quantity of liquid collects close to the line of contact between the film and rollers, the presence of which is not common knowledge; or, at least, the presence of which has been ignored in the past. This col lection of liquid on the dry side of the rollers acts to rewet the film surface and impairs the quality of the results obtained by the use of wringer rolls alone. Accordingly, wringer rolls alone cannot be relied upon to completely remove all surface liquid from a web. While air squeegees are more efficient than wringer rollers in removing surface liquid, when used alone they require large amounts of air which, in turn, requires a large amount of power and causes a considerable amount of noise.

One object of the present invention is to combine the conventional wringer rollers with an air squeegee in such a way that the above-mentioned drawbacks of each is overcome and a drying action is obtained which is much more efficient than any which could be obtained by the individual use of either means, or by the successive use of the two.

Another object is to provide a method of removing the superfluous liquid from a film surface which comprises passing the web between a pair of wringer rollers and continually removing the bead of liquid formed between the film surface and the nip of the rollers on the downstream and/or upstream side of the rollers by the use of air blasts.

And, another object is to provide a combined wringer roll-ainsqueegee arrangement wherein 4 Claims. (Cl. 34-14) air jets are located adjacent the downstream and/or upstream side of the rollers and so disposed as to direct jets of air at an angle into the interface between each surface of the film and the surface of the roller engaged thereby to continually remove any bead of liquid formed at these points.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself. however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection withv the accompanying drawings; in which Fig. 1 is an end sectional detail showing a wet film passing between a pair of conventional wringer rollers and showing how a bead of liquid is formed on both the upstream and downstream sides of the rollers;

Fig. 2 is a longitudinal sectional detail of one end of a pair of wringer rollers showing a perforated moving-picture film passing through a pair of resilient wringer rollers and illustrating how liquid is carried to the downstream side of the rollers to form a bead at this point which rewets the film surface;

Fig. 3 is an elevational end view of a combined wringer-roller-air squeegee constructed in accordance with a preferred embodiment of the present invention;

Fig. 4 is an elevational end view showing another embodiment of the present invention; and

Fig. 5 is a view, partly in section and partly in elevation, showing my combined wringer roller-air squeegee in association with the last processing tank (usually the washing tank) of a film-processing machine.

Like reference characters refer to corresponding parts throughout the drawings.

Referring to Figs. 1 and 2, it is well known that when a wet film F is passed between two wringer rollers l0 and II that a quantity of the liquid squeezed from the film collects on the upstream or "wet side of the wringer rollers in the form of beads l2 and I3 which form between the respective surfaces of the film and the surface of the roller engaged thereby. While these two beads may be considered as a single bead divided by the film passing therethrough, especially if the film extends right to the ends of the wringer rollers, for the purpose of the present disclosure this accumulation of liquid will be considered as two separate beads. The liquid accumulated in these beads is allowed to flow off the edges of the film, and it is assumed that thefilm as it passes from the rollers, is freed of substantially all surface liquid.

Contrary to assumed knowledge, I have found that another smaller quantity of liquid also collects close to the line of contact between the film and rollers on the downstream or "dry" side of the rpllers in the form of beads l4 and I5, and that this collection of liquid acts to rewet the film surfaces and impairs the quality of the results obtained by this method of drying a film. I have found that this accumulation of liquid on the downstream side of the roller persists regardless of the degree of compression between the rollers or the character of the material from which the roller surfaces are made.

One of the principal reasons why the beads I4 and I5 of liquid collect on the downstream side of tightly-compressed rollers is that an opening ordinarily exists at both edges of the film,-as shown at iii in Fig. 2. Here the rollers do not make contact, even if fabricated of a compressible material, so that liquid which passes through the opening can distribute itself by capillarity on the downstream side of the wringer rollers as beads l4 and 15. If the film being squeeged is a motion-picture film which is provided with perfora ions along its margins, one being shown at I8 in Fig. 2, then another reason for the formation of the beads I4 and [5 on the downstream side of the rollers is that a quantity of liquid is carried from the beads l2 and I3 between the rollers by each of these perforations. Other reasons for the presence of these beads l4 and I5 on the downstream side of the rollers may exist, but they need not be investigated, or considered, in the present disclosure; the fact that such beads do exist being suflicient to an understanding of the utility and operation of the present invention.

I have found that if the concentration of liquid on either the upstream, or downstream, side of the wringer rollers is continuously removed, the effectiveness of the roller squeegee increases greatly. Therefore, according to the present invention, the beads of liquid which collect on one, or both sides of a pair of wringer rollers is continuously dispersed, or removed, by a suitably directed jet of air delivered under pressure from a nozzle. A preferred embodiment of the present invention is shown in Fig. 3 wherein a pair of nozzles 24 and 25 are disposed above and below the film at the downstream side of the wringer rollers, the nozzle 24 being directed at the bead l4 and the nozzle 25 being directed at the bead l5. These nozzles are connected to a source of air 'under pressure, not shown.-

I have found that the shape and dimension of the discharge ends of the nozzles are not very critical, although the shape, dimension, and number of the nozzles used may vary with the width of the film being dried. I have found that a nozzle having a -inch inside diameter discharge end directed perpendicularly to the center of nip of the wringer rollers will completely disperse the beads of liquid from a 16-mm. film. The

confining action of the channel formed between 4 necessary to use a plurality of air jets displaced across the width of the film and relatively disposed to produce the desired sweeping action laterally of the film, or longitudinally of the rollers. The direction of the nozzles is not too critical in this device when narrowfilms are being dried, it only being necessary that the air stream be directed toward the apex of the angle formed by the surface of the roller and the film. This narrowing channel confines and concentrates the force of the air jet, directed into that space, to the area where the head of liquid is caused to collect by the rollers.

Because of this action, considerably less air is needed to disperse these beads of liquid than would normally be required when the energy of th jet is allowed to dissipate-itself over a larger area, as is true in the normal air squeegee application of air jets. The cumulative effect of this combination of wringer rollers and air jets is considerably greater than the sum of the individual effects which can be attributed to each device separately. By the use of this combination of parts and functions, a significant economy of compressed air is attained, while the thoroughness of squeegeeing, obtainable by the use of wringer rollers and an air squeegee alone, is much improved.

The efficiency of the present combined wringer roller-air squeegee arrangement can be increased to some extent by adding the two air jets 26 and 21, as shown in the embodiment of Fig. 4 which act to disperse the beads of liquid I2 and I3 which form between the rollers and the film surfaces on the upstream or wet side of the rollers. These two additional jets merely reduce the amount of liquid present which might be carried between the rollers toform beads l4 and I5 and reduce the amount of work required of jets 24 and 25. It will be obvious that the usefulness of these two jets 26 and 21 is much less than that of jets 24 and 25 for which reason the increase in efficiency of the combination is hardly sufficient to warrant the added expense of application and operation of these two jets 26 and 21. This conclusion, of course, is based upon the fact that the jets 24 and 25 are operating at maximum efliciency and are capable of completely dispersing the beads I 4 and I5 which tend to form on the downstream side of the rollers. If, for any reason, the amount of liquid carried through the rollers to the downstream side thereof is so great as to tend to form beads l4 and I5, which are too large for jets 24 and 25 to completely disperse continuously, these jets 26 and 21 will be useful to reduce the amount of liquid formin beads l2 and I3 which will be available to be carried between the rollers.

For ordinary applications I have found that only jets at the downstream side of the wringer rollers are necessary, and in Fig. 5 I have diagrammatically illustrated this embodiment of the invention in operative association with a part of a film-processing machine. In Fig. 5 only the washing tank 30 of a film-processing machine is shown. The film F, after leaving a previous processing bath (fixing solution), is passed, by the aid of guide rollers 3|, in a loop through water W in the tank 30 to become completely washed free of processing solutions. Immediately after leaving the washing tank, the film is passed through a combined wringer roller-air squeegee constructed in accordance with the embodiment shown in Fig. 3, and thence through a drying means prior to being wound up. This combined wringer roller-air squeegeehas been found to so effectively remove all surface moisture from the film surfaces that it can be completely dried in such a short time as to make direct wind-up .possibie. If one feels the .base side of the film, leaving'the combined wringer roller-air squeegee with his fiingers, it will feel perfectly dry, showing that all surface moisture has been removed. However, if the air squeegee is shut off momentarily, this side of the film will immediately feel wet to the touch, proving that the wringer rollers alone are not capable of doing a thorough job of removing surface moisture from a film.

It is pointed out that suction can be utilized to remove the liquid collected as beads in the above-described crevices between the roller and film surfaces. However, because it is not possible to create a directive suction jet which can function in the manner of a "pressure jet, and thereby penetrate in its effect to the apex 0f.the roller-film angle, the effectiveness of such a scheme will be less than when pressure Jets are used as set forth.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be limited to the precise details of construction shown and described, but is intended to cover all modifications coming within the scope of the appended claims.

Having thus described by invention, what I claim is new and desire to secure by Letters Patent of the United States is:

1. The method of removing the excess liquid from the body and surface of a wet film of absorbent material and comprising the steps of moving the film between a pair of wringer rollers to squeegee the liquid therefrom, and blowing a blast of air substantially normally to the nip between the rollers and web surfaces to continuously disperse the head of liquid formed between the opposite faces of the film and the roller surfaces at thedownstream side of said rollers to prevent said beads of liquid from rewetting the film faces as the film leaves the wringer rollers.

2. The method of removing th excess liquid from the body and surface of a wet film of absorbent material and comprising the steps of moving the film between a pair of wringer rollers to squeeze the liquid therefrom, and blowing a blast of air substantially normally to the nip between the rollers and web surfaces to continuously disperse the bead of liquid formed between the opposite faces of the film and the roller surfaces at both the upstream and downstream side of said wringer rollers.

3. The method of removing the excess liquid from the body and surface of a wet film and comprising the steps of moving the film between a pair of wringer rollers to squeez the liquid therefrom, and continuously directing an air blast substantially normally into the apices of the angles formed between opposite faces of the film and the roller surfaces engaged thereby at the downstream side of said wringer rollers to disperse the beads of liquid formed at these points and prevent them from rewetting the film faces as the film leaves the wringer rollers.

4. A method of removing the excess liquid from the body and surface of a wet film according to claim 3, and includingthe step continuously directing an air blast substantially normally into the apices of the angles formed between opposite faces of the film and the roller surfaces engaged thereby at the upstream side of said wringer rollers to disperse the beads of liquid formed at these points and reduce the amount of liquid available to be carried between the rollers for formation of the beads of liquid at the downstream side of said rollers.

CHARLES J. KUNZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,746,431 Kolitsch Feb. 11, 1930 1,816,290 Klimis July 28, 1931 1,839,105 Long Dec. 29, 1931 2,234,153 Herbert Mar. 4, 1941 2,234,697 Hickman Mar. 11, 1941 2,289,753 Capstaif July 14, 1942 

